ENH: validate optional fractional seconds in acqTime

bids-validator/validators/tsv/checkAcqTimeFormat.js

@@ -2,17 +2,34 @@ const Issue = require('../../utils').issues.Issue
 import { isValid as dateIsValid, parse } from 'date-fns'
 
 const checkAcqTimeFormat = function(rows, file, issues) {
-  const format = "yyyy-MM-dd'T'HH:mm:ss"
   const header = rows[0]
   const acqTimeColumn = header.indexOf('acq_time')
   const testRows = rows.slice(1)
   testRows.map((line, i) => {
+    var format = "yyyy-MM-dd'T'HH:mm:ss"
     const lineValues = line
     const acqTime = lineValues[acqTimeColumn]
-    let isValid = dateIsValid(parse(acqTime, format, new Date()))
-    if (acqTime === 'n/a') {
-      isValid = true
+    // Try different date formats: We accept any amount of optional fractional
+    // seconds: .S, .SS, .SSS, .SSSS, .SSSSS, .SSSSSS
+    var isValid = false
+    for (i = 0; i < 7; i++) {
+
+      isValid = dateIsValid(parse(acqTime, format, new Date()))
+
+      // exit early if date is valid or n/a
+      if (acqTime === 'n/a' | isValid) {
+        isValid = true
+        break
+      }
+
+      // If not valid, try again with parsing a new amount of fractional secs
+      if (i === 0) {
+        format += '.'
+      }
+      format += 'S'
     }
+
+    // if the loop exits with !isValid, we need to raise an issue
     if (acqTime && !isValid) {
       issues.push(
         new Issue({